Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
2002-06-19
2004-02-03
Deb, Anjan K. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C324S071200, C073S007000, C055S435000
Reexamination Certificate
active
06686752
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to erosion or wear indicators on refractory linings. More particularly, it relates to an electrical conductor embedded in a refractory or liner in a vessel, wherein the continuity of the conductor is monitored such that, when the refractory or liner is worn beyond the level at which the conductor is embedded, the conductor is also eroded, either increasing the resistance of the conductor, or completely breaking the conductor (creating an infinite resistance) and indicating an open circuit.
It is understood that this invention may be used in any vessel where it is advantageous to monitor the wear on the vessel liner so that a scheduled repair or replacement may be implemented, instead of an unscheduled emergency shutdown.
Cyclone separators are often used as primary gas pollution control equipment, ahead of baghouses, for instance, to knock out the larger particles and reduce the particulate loading on the baghouse. The abrasive action of the particles, swirling in a spiral path at high velocity against the inside wall of the cyclone separator, results in accelerated erosion, which can result in sudden failure of the cyclone separator.
If the system needs to undergo an emergency shutdown, it may be difficult to start the system up again, especially in systems which operate at high temperatures, where the product being processed may solidify at ambient temperatures. Advance notice of the impending failure of the eroded part would be advantageous, both to prevent damage to the vessel and so that a planned shutdown for maintenance can be scheduled.
SUMMARY OF THE INVENTION
The present invention provides a conductor wire embedded in the refractory or liner (hereinafter collectively referred to as “refractory lining” or “refractory”) of the vessel to be monitored for wear. As erosion wears the refractory, the conductor wire will eventually be exposed to the abrasive action of the gas flow stream, and it will also be subject to erosion. A simple ohmmeter connected at the two ends of the wire monitors the conductivity (or resistivity) of the wire circuit. When the wire is intact, the resistance is very low. As the wire erodes, the resistance increases. Once the wire is severed by the action of the erosion, the resistance goes to infinity, indicating an open circuit.
Monitoring with the ohmmeter may be continuous, or it may be on an intermittent basis, such as once a shift. When the meter first indicates a change in conductivity, the operator takes note and can decide when to schedule a planned shutdown for repairs. If the wire was buried approximately halfway between the original, inner exposed wall of the refractory and the inner wall of the vessel, and it took, for instance, six months to begin to erode the wire or to reach the “broken wire” condition, then the operator may reasonably assume that it will be approximately six more months before all the refractory is fully eroded and the cyclone separator wall itself will be under attack.
He can then schedule maintenance accordingly.
It should be noted that the conductor wire embedded in the refractory or liner preferably is an electrically insulated conductor to ensure that the conductor itself does not short out against the vessel wall or against metal clips which may be used to secure the refractory against the vessel wall, giving a false continuity indication of the conductor. Also, the conductor wire preferably extends along a substantial vertical distance of the vessel, increasing the likelihood that wear of the vessel will be sensed by the conductor wire, as opposed to many prior art sensors, which are located at only a single point in the vessel.
REFERENCES:
patent: 2915305 (1959-12-01), Craig
patent: 3078707 (1963-02-01), Weaver
patent: 4092848 (1978-06-01), Thomas
patent: 4103539 (1978-08-01), Worley
patent: 4269397 (1981-05-01), Strimple et al.
patent: 4646001 (1987-02-01), Baldwin et al.
patent: 6208128 (2001-03-01), Braconnier et al.
patent: 6265880 (2001-07-01), Born et al.
patent: 1 341 814 (1973-12-01), None
patent: 1 603 741 (1981-11-01), None
Elvin Frank
Heumann William L.
Lewis Russell J.
Miller James F.
Noppenberger Mark T.
Camoriano Guillermo
Camoriano Theresa Fritz
Camoriano and Associates
Deb Anjan K.
Fisher-Klosterman, Inc.
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